Ureido thickened greases



and to the method of preparing same. .it relates-to novel greasescomprisingv a lubricant vehicle such as silica gels.

lubrication at elevated temperatures.

United States Patent -UREIDO THICKENED GREASES Edward A. Swakon,Hammond, Ind., assignor to Standard Oil Company,'Chicago, 111., acorporation of Indiana N Drawing. Application June 13, 1955 .Serial No.515,257

13 Claims. (Cl; 252-49.6)

The present invention relates to novel lubricant greases Moreparticularly,

thickened with certain high melting ureido compounds. Greases of thistype have demonstrated exceptional stability at elevatedtemperatures.

As lubricants are required toperform at higher and higher temperaturesbecause of increased speeds of engines and machines, the advent of jetpropulsion, atomic energy as a source ofppowenetc, it has becomeincreasingly .diflicult to preparegreases fulfilling the requirements ofsuch lubricants. In attempting to provide such greases, the art hasprogressed from the use of petroleum lubricant vehicles thickened withmetal soapsof long chain fatty acids, e. g. lithium hydroxy-stearate, tomore thermally stable synthetic lubricating oils such as the aliphaticdiesters of dicarboxylic-acids, silicone polymers,

etc., thickened with such soaps or inorganic materials The progress ofthickener research has not in general, however, kept pace with thedevelopment of lubricant vehicles. And at temperaturesas high as 400 to450 F. thereare few if anygreases available which will retain theirconsistency and lubricity for any substantial period of time.

In recent years various synthetic lubricant vehicles, e. g. thesilicones, fiuorocarbons, etc., have been foundto be potentiallyvaluable for use in greases employed at very high temperatures becauseof their thermal stability and relatively low volatility. Unless,however, a thickener having substantially the same degree of thermalstability is available to produce a grease from such an oil, they are oflittle use.

It is a-primary object of the present invention to provide lubricantgreases which are stable and give excellent A further object is toprovide :a readily producible series of greases embodying a novel classof thickening agents capable of yielding lubricants particularlysuitable for use at temperatures of fromabout 250 F. to about 450 Aparticular object of the present invention is to provide greases whichare effective lubricants at temperatures as high as a about 450 F. forsubstantial periods of -time. These and additional objects will beapparent from the 'tollowingdetailed description.

Copending Swakon andBrannen application for Letters 'Patent S. N.318,321, filed November 1, 1952, now US. 2,710,839, discloses-andclaimscertainvery high melting aromatic ureas, diureas, amides, and diamides,all of which contain at least one silicone polymer oils, as well asother known lubricant I vehicles, to produce greases which are stableand display excellent lubricant properties over a wide range oftemperatures. Whereas silicone polymer oils are particularly 2,832,739Patented.Apr-.29, 11958 preferred for use. in. greases. employed attemperatures as prising mixtures .of atleast two different arylsubstituted meats and/ or diureas are described and claimed. .Thus,

inv accordance with the invention described in said. application,mixtures of aryl. substitutedureas,preparedlbynreacting (1) at leasttwoditferentaryl monoisocyanates with :at least one aryl amine(monoordi-amine) .or (2) atleast t-Wodifferent aryl monoamines with atleast one aryl .isocyanate Y (mono-. ordiisocyanate) It has now been.found thatgrease compositions exhibiting good rheological properties,.having high thermal stability and possessinghighdropping pointsand/or.,.nomelt characteristics can be. obtained by thickeningasuitableoleaginous lubricant vehiclewlth. from about 2% to/about 50% andpreferably fromabout 5% to about 40%,-by weight,- of a ureidocompoundhaving-the general formula in which Z and Z are terminal reactiveradicals selected from the group consisting of .NH and-NCO' radicalsalkylene groups are further characterized-as straight and/ .or branched.chain, radicals having from ,1 to i about-30 .carbon. .The .arylene andsubstituted ar-ylene.radicals can be mononuclear and/or polynuclear-suchas phenylene,

.biphenylene,. naphthylene and anthrylene radicals.

.The ureidocompounds are readily prepared by heating a mixture of thepolyamine and the polyisocyanate. in equivalent weight ratios of fromlzx to x11 Where x can be anumber rangingfrom-Z to 4, and preferablyinlthe equivalent weight ratio of 1:1, at a temperaturew'ithin the rangeof room temperatu-ret about -F.) to about 350 F. .For example;-when"diamines-and diisocya'nates are the reactants the equivalentweight ratioca-nbe varied from 1:2 to 2:1, While whenltr-iamines andtriisocyanates are the reactants the equivalent weight ratio can bevaried One or more'polyamines can be reacted with one or morepolyisocyanates to give mixed polyureido compounds. Asindicated in thegeneral formula above, the herein described ureido compounds can haveone aminoand one isocyano-terminal radical or both terminalradic-alscanbe the same, i. e. either amino rradicals or-isocyano radicalsdepending upon the equivalent weight ratio of the reactants used. Thuswhen the polyamine and the polyisocyanate are used in the equivalentweight ratio of 11:1, the resultant reaction products will containpredominantly ureido compounds having amino and isocyano terminalradicals; when the :reaction mixture contains an excess of thepolyamine, the .resultant reaction products will contain ureidocompounds the terminal groups of which are predominantlyamino radicalls,.and whenthe viteactionmixture contains an :excess 10 10f" thepol-yisocyanate, reaction products containing ureido compounds havingpredominantly lSOCYfiIIDw-tfil'fillll'tll groups will be obtained.

When the polyamine is a diamine and the polyisocyanate is a diisocyanatethe resultant polyureido compounds are linear. However, if one or moreof the reactants is a polyamine greater than a diamine, for example, a

f triamine, such as l,3,5-triaminobenzene,'or the polyisocyanate isgreater than a diisocyanate, for example, a -triisocyanate, such as,1,3,5-benzenetriisocyanate, crossadded, some of the terminal free aminesare blocked and transformed to phenyl ureido groups.

Examples of suitable polyisocyanates which can be employed in accordanceherewith are tolylene diisocyanate, p,p'-diisocyanate biphenyl,1,4-diisocyanato-ben zene, p,p'-diisocyanato-diphenylmethane,1,6-diisocyanato hexane, 1,12-diisocyanato dodecane, 1,3,5-benzenetriisocyanate, naphthylenediisocyanate, bitolylene diisocyanate,tris-p-isocyanatophenyl-methane.

Examples of suitable polyamines are benzidine, p-phenylene-diamine,o-phenylenediamine, m-phenylenediamine,

o-tolidine, triamino-benzene, 1,6-diaminohexane, 1,10-diaminodecane,

1,3-diaminopropane, dialkylenetriamine, trialkylenetetramine,ethylenediamine, xylylenediamine, tolylenediamine,dimethyl-p-phenylenediamine, etc.

Polyureido compounds of the type hereindescribed can be prepared by thereaction of water on a polyisocyanate in accordance with the probablereaction as illustrated by the following equations:

where the R represents organic radicals as above defined.

(While the reaction of the polyamine and the polyisocyanate in a moleratio of 1:1 will give ureido compounds having aminoandisocyano-terminal radicals, in the above preparation wherein thepolyamine is first obtained by the hydrolysis of the polyisocyanate,excess water present as indicated for the last reaction, hydrolyzes theisocyanoterminal radical of the final product to an amino-radical.)

The above reaction is illustrated by the following specific exampleusing bitolylene diisocyanate:

I (oTolldine) a polymer such as The general structural formulae ofillustrative ureido compounds of the type herein described are:

wherein Ar represents a phenylene radical, Ar represents a biphenyleneradical, R represents a (CH alkylene radical, R represents a (CHalkylene radical and R" represents (CH alkylene radical.

While the above formulae are illustrative of ureido compounds containingan aminoand an isocyano-terminal group, the present invention is notlimited to such ureido compounds, but includes ureido compounds havingamino-terminal groups or isocyano-terminal groups, as shown by thegeneral formulae given above.

Oleaginous lubricant vehicles which can be thickened with the hereindescribed polyureido compounds to form greases of the present inventioncan be silicone polymer oils, mineral lubricating oils, synthetichydrocarbon lubricating oils, synthetic lubricatingoilssuchaspolyalkylene glycols and their derivatives, high molecularWeight esters of dicarboxylic acids, polyfluoro derivatives of organiccompounds such as the trifluorovinyl chloride polymers known asFluorolube (made by Hooker Chemical Company) and thetrifluorochloroethylene polymers,

known as Kel-F-40 (made by The M. W. Kellogg Company), and otherlubricant vehicles.

The silicone polymer oils which may be employed in accordance with thepresent invention are those falling substantially within the lubricatingoil viscosity range. In general, such oils have the following unitstructure:

wherein Rand R represent substituted or unsubstituted alkyl, aryl,alkylaryl, arylalkyl or cycloalkyl radicals. Such compounds may beproduced by well-known methods, e. g. the hydrolysis ordialkyldichlorosilanes or dialkyldiethoxysilanes with a suitable chainstopper, e. g. a trisubstituted mono-chlorosilane. For purposes of thepresent invention, those polymers which are high boiling liquids withinthe lubricating oil viscosity range are suitable, these generallypossessing a viscosity at F. which is within the range of from about 25to about 3500 S. S. U. It is preferred, for purposes hereof, to employsuch oils as have a viscosity at 100 F. of from aboutlOO S. S. U. toabout 1250 S. S. U. Such products are generally colorless and inert,have a very low volatility and undergo relatively slight change inviscosity for a given change in temperature. Relatively common oils ofthis type are dirnethylsilicone polymer, phenylmethylsilicone polymer,chlorophenylmethylsilicone polymer, etc., it being preferred to employeither the phenylmethylsilicone or the chlorophenylmethylsiliconepolymer in accordance herewith. Methods .of preparing such compounds are5 taught in numerous patents, e. g. U. S. 2,410,346,11. S 2,456,496, andin the literature such as Chemistry of the Silicones, by Rochow, page61, et seq. A particularly desirable phenylmethylsilicone polymer foruse in accordance with the present invention is Dow-Corning 550 SiliconeFluid, a product of Dow-Corning, Inc, which has a Saybolt Universalviscosity at 100 F. of about300 to about 400 seconds. Another suitablesilicone polymer is a chlorophenylmethylsilicone marketed as GE 81406 byGeneral Electric Company.

Other oleaginous vehicles which may be employed herewith are, forexample, mineral oils in the lubricating oil viscosity range, i. e. fromabout 50 S. S. U. at 100 F. to about 300 S. S. U. at 210 F; Thesemineral oils are preferably solvent extracted, to substantially removethe low V. I. constituents, e. g. aromatics, with phenol, furfural,B,B'-dichlorodiethylether (Chlorex), liquid S nitrobenzene, etc.Synthetic lubricating oils resulting from polymerization of unsaturatedhydrocarbons or other oleaginous materials within the lubricating oilviscosity range such as high molecular weight polyoxyalkylene compoundssuch as polyalkylene glycols and esters thereof, aliphatic diesters ofdicarboxylic acids such as the butyl, hexyl, 2-ethylhexyl, decyl,lauryl, etc., esters of sebacic acid, adipic acid, azeleic acid, etc.,may be thickened by the ureido compounds of the present invention toproduce excellent greases. Polyfiuoro derivatives of organic compounds,particularly hydrocarbons and dibasic acid esters of H(CF ),,CH OH, inthe lubricating oil viscosity range have shown excellent promise whenthickened with compounds of the present invention.

Greases of the present invention may be produced by one of the followingmethods:

(1) The thickener may be prepared apart from and then admixed with thelubricant vehicle and milled in a colloid mill, 3-roll mill, etc.

(2) The thickener may be formed in situ in the oil by introducing thereactants and the desired amount of lubricant vehicle, heating for arelatively short time, e. g. from about five minutes to an hour tocomplete the reaction, and then cooling and milling the mixture.

(3) As a slight modification of method 2 above, a solvent such aschloroform, ethyl acetate, dioxane, 2-butanone, benzene, etc., may beemployed as a diluent and mutual solvent for the reactants. The solventis then evaporated and the grease is milled, etc., substantially as setforth. Co-pending Swakon and Brannen application for Letters PatentSerial Number 392,996, filed November 18, 1953, now U. S. 2,710,841, isdirected to the preparation of substituted urea thickened greasesgenerally by the in situ technique.

(4) As a step in any of the above three methods, it has been found thatimproved properties may be imparted to the grease by heat-treating thegrease mixture, i. e. subjecting the same to an elevated temperature forat least about half an hour and preferably longer, e. g. from about 1 to20 hours. Prolonged heating at such temperature may evaporate a portionof the lubricant vehicle; this loss should be replaced and then themixture should be milled. The temperature to which the mixture may beheated will, of course, depend upon the particular lubricant vehicleemployed. Thus, a silicone polymer oil may be heated to a temperature ofabout 450 F. but mineral oils, diesters, and other synthetic oils may beheated from about 200 to 400.

The present invention is illustrated by the following examples:

Example I One-hundredth of mole (1.84 grams) of benzidine, dissolved inethyl acetate, was added to one-hundredth of mole (2.5 grams) ofp,p'-diisocyanato-diphenylmethane in a solvent-extracted SAE 40petroleum oil (17.4 grams). An immediate reaction occurred whichresulted in the thickening of the mixture. The mix was heated and the 6.se i'sm .remq s y d sti lat qs- Afte sth salvea was remo e t e reultant p odust as hea ed to 30.0 o ed n an o n t 3 .F- for two hours, coled-t about 80 F., and then milled. The finished grease conm n 2 o P dmi antly t e po y-ure do ompo was a m t ho -fib ed p oduct h ng amicropen t a io 1 o 16.8-

Example II A polyureido thickened solvent extracted SAE 40 petroleum oilwas prepared as in Example I, usingonehu d h 1.1101e 1 -08 m f p-p l n dsm ss i P a of h b n i Th nished r asep dus ,-sentaining of thepolyureido compound was smooth and short-fibred and had amicropenetration of .60.

Example III A mixture of one-fiftiethmole (5.0 grams) o f p-p'-.diisocyanatodiphenylmethane in a solvent extracted SAE 40 petroleum oiland one-hundredth mole each of benzidine (1.84 grams)andp-phenylenediamine (1.08 grams) dissolved in ethyl acetate was heatedat 300 F. for about fifteen minutes and the solvent removed byevaporation. The solvent-free product was then stored at 300 F. for twohours, cooled to 80 F., and then milled. Th finished grease productcontaining 20% of the polyureido compound was smooth and short-fibredand had a micro penetrationof 78.

The stability of polyureido thickened greases is illustrated by thefollowing micropenetration data on the greases after being held at 300F. for one, two, and three days.

Mlcropenetratton (after milling) r r a A Initial One Two Three Day DaysDays Grease of Example I 168 148 177 15s Grease of Example 11... so 87us 154 Grease of Example III 78 54 58 00 3x5115 811, G., Finn, .T., andHarrington, .T., Ind. Eng. Chem., Anal. Ed., 11, 108 (1939).

Example I V An intimate, mixture of DC 550 Silicone Fluid and dry powderfrom the reaction of bitolylene diisocyanate and water was passed over athree-roll mill. The resulting product is a bright, smooth paste..Penetration data on application Ser. No. 318.321 (supra) at 450 F. and10,000 R. P. M. ran 211 and 344 hours.

Example V Grease made by method used in Example IV exceptdiisooctylazelate used in place of DC 550 Silicone Fluid.

The resulting grease .containing 12.5% thickener had a At-size conepenetration of 63.

Example VI using a solvent-extracted SAE 40 grade petroleum oil had aAt-size penetration of 72 with 15% concentration of thickener.

1 Kaufman, G., Finn w. 1., and Harrington, R. J., Ind. Eng.

75 Chem, Anal. Ed, 11, 108 (1939 Grease made by the method used inExample IV and I Greases of the present invention can contain well knownadditives such as anti-oxidants, oiliness agents, extreme pressureagents, anti-foam agents, etc. without departing from the scope of theinvention.

Although the present invention has been described with reference tospecific preferred embodiments thereof, the invention is not to beconsidered as. limited thereto, but includes within its scope suchmodifications and variations as come within the spirit of the appendedclaims.

I claim:

1. A lubricant grease comprising a lubricant vehicle thickened with fromabout 2% to about 50%, by weight, of at least one ureido compound havingthe general formula wherein Z and Z are terminal reactive radicalsselected from the group consisting of NH; and -'NCO radicals andmixtures thereof, x is an integer to 5, and R, R, and R" are organicradicals selected from the group consisting of an alkylene radical, asubstituted alkylene radical, an arylene radical, a substituted aryleneradical and mixtures thereof, said alkylene radical and substitutedalkylene radical having 1 to about 30 carbon atoms, and said arylene andsubstituted arylene radical having no more than 14 cyclic carbon atoms.

2. A lubricant grease as described in claim 1 in which the lubricant isa hydrocarbon lubricating oil.

3. A lubricant grease as described in claim 1 in which the lubricantvehicle is a silicone polymer oil in the lubricating oil viscosityrange.

4. A lubricant grease as described in claim 1 in which the lubricantvehicle is an acyclic ester of an aliphatic dicarboxylic acid.

5. A lubricant grease as described in claim 1 in which the lubricantvehicle is a polyfluoro-compound in the lubricating oil viscosity range.

6. A lubricant grease as described in claim 1 in which R, R, and R" areorganic radicals selected from the group consisting of an aryleneradical, a substituted arylene radical, and mixtures thereof, saidarylene and substituted arylene radicals having not more than l4 c,ycliccarbon atoms.

7. A lubricant grease as described in claim 1 in which R, R, and R areorganic radicals selected from the group consisting of an alkyleneradical, a substituted alkylene radical and mixtures thereof, saidalkylene and substituted alkylene radicals containing from 1 to about 30carbon atoms.

8. A lubricant grease comprising a lubricant vehicle thickened with fromabout 2% to about 50%, by weight, of at least one polyureido compoundhaving the general formula 'stituted arylene radical having no more than14 cyclic carbon atoms.

9. A lubricant grease comprising a lubricant vehicle thickened with fromabout 5% to about 40%, by weight, of a polyureido compound having theformula in which R is a phenylene radical.

10. A lubricant grease comprising a lubricant vehicle thickened withfrom about 5% to about 40%, by weight, of a polyureido compound havingthe formula in which R is a bitolylene radical.

11. A lubricant grease comprising a lubricant vehicle thickened withfrom about 5% to about 40%, by weight, of a polyureido compound havingthe formula in which R is a phenylene radical and R' is a bipheyleneradical.

12. A lubricant grease comprising a lubricant vehicle thickened withfrom about 5% to about 40%, by weight, of a polyureido compound havingthe formula:

H N--(CI-I NH-CONH( CH NHCONH(CH NCO 13. A lubricant grease comprising alubricant vehicle thickened with from about 5% to about 40%, by weight,of a polyureido compound having the formula in which Ar represents aphenylene radical.

References Cited in the file of this patent UNITED STATES PATENTS2,292,443 Hanford Aug. 11, 1942 2,710,839 Swakon et a1 June 14, 19552,710,840 Swakon et a1 June 14, 1955 2,710,841 Swakon et a1 June l4,1955 U. 5. DEPARTMENT OF COMMERCE PATENT OFFICE CERTIFICATE 0FCORRECTION Patent No, 2,832,739 Edward A, Swakon It is hereby certifiedthat error appears .in the printed specification of the above numberedpatent requiring correction and that the said Letters April 29, 1958Patent should read as corrected below.

Column 2, line 25, for that portion of the formula reading "(NH-CO-NH-Rread (NH-CO-NH-R"-) column 8, line 27, extreme left-hand portion of theformula, for "H H-" read H N-'- Signed and sealed this let day of July1958.

(SEAL) Attest:

KARL H AXLINE ROBERT C. WATSON Attesting Officer Conmissioner of Patents

1. A LUBRICANT GREASE COMPRISING A LUBRICANT VEHICLE THICKENED WITH FROMABOUT 2% TO ABOUT 50%, BY WEIGHT OF AT LEASR ONE UREIDO COMPOUND HAVINGTHE GEANRAL FORMULA